I woke up this morning to hear an item about astronomy on the 7 o’clock news on BBC Radio 3. That doesn’t happen very often so I thought I’d follow it up with a short post before I head off to work.

The news item I heard followed up an announcement yesterday that the governing Council of the European Southern Observatory (ESO) had approved the European Extremely Large Telescope (E-ELT) programme – which is to produce what will be the world’s largest ground-based optical telescope. Extremely Large is putting in mildly, of course. Its main mirror will be a colossal 39 metres in diameter (with a collecting area of almost a thousand square metres) and will have to made in bits with a sophisticated adaptive optics system to ensure that it can counter the effects of the Earth’s atmosphere and the limitations of its own structure to reach a phenomenal angular resolution of 0.001 arc seconds.

For more details on the telescope, see the official website here or the wikipedia article here, where you can also read more about the science to be done with E-ELT.

This telescope has been in planning for many years, of course. In fact, it began as an even more ambitious concept, a 100-metre diameter monster which I used to call the FLT. Over the years, however, for a mixture of technical and financial reasons, this was progressively de-scoped.

Yesterday’s announcement doesn’t mean that work will start immediately on building the E-ELT. That won’t happen until sufficient funding is secured and in the case of some countries, governmental approval obtained. Recent decisions by the UK Science and Technology Facilities Council to close down telescopes in Hawaii clearly anticipated the need to make some headroom in future budgets to enable this to happen. The best-case scenario is probably for E-ELT to take a decade or so to complete.

Of course the concentration of funding in ever and ever larger international facilities – such as E-ELT and the Square Kilometre Array – does create tensions within the UK astronomical community. Many scientists do excellent work with relatively small facilities, including those about to be closed down to make room for E-ELT. In the near future, the only ground-based optical facilities to which UK astronomers will have access will be operated by the European Southern Observatory. With fewer but larger (and more expensive) facilities operated by international agencies carrying out projects run by vast consortia, observational astronomy is definitely going the way of particle physics…

Reviews of this kind would be necessary in the best of times in order to establish long-term scientific priorities and try to align the provision of facilities with those strategic objectives. Unfortunately, we don’t live in the best of times so the backdrop to the current review is a shrinking pot of money available for “traditional” ground-based astronomy and the consequent need to target planned programmes for the chop.

Andy and Sarah have already blogged about this -and they both know a lot more than me about ground-based astronomy – so I won’t try to cover the same ground as them. I would however, like to make a couple of points.

The review has to help STFC strike a balance between current facilities and projects for the future. The largest elements of the current ground-based programme include the subscription to ESO (including associated costs for ALMA, which amounts to over £200 Million), the twin 8m telescopes known as Gemini (North and South, about £60 Million), E-Merlin (about £24 Million), UKIRT and JCMT (about £34 Million); figures represent costs over the next 10 years or so. The two biggest projects that the UK would like to get involved in are a European Extremely Large Telescope (E-ELT), an optical telescope currently aimed to be about 42m in diameter, and the Square Kilometre Array, a futuristic radio telescope. Each of these would cost the UK over £100 Million over the next decade.

The consultation document puts it quite succintly:

It would be unrealistic to imagine that in 2020 the UK would have a large stake in large facilities like E-ELT and SKA, and would also retain all its current ground-based facilities. It is always hard to forego a workhorse facility that has supported an active and successful science programme, in order to start construction of some future facility many years hence. But our bid for the capital costs for E-ELT and/or SKA would not be credible if we do not show that we are willing to do this.

I agree that it maintaining the current programme as well as acquiring an interest in both E-ELT and SKA is completely implausible. The more relevant question though is how deep we have to cut the ongoing astronomy programme in order to afford either of these, or whether we can do that at all. It seems quite likely to me that future funding of the ground-based programme is likely to suffer drastically, both because of cuts to the overall STFC grant that appear inevitable in the next comprehensive spending review and also the current STFC leadership’s bias in favour of space technology at the expense of science. On the latter point, it is worth noting that it is specifically the ground-based astronomy programme that is being lined up against the wall here; space-based projects of negligible scientific value, such as Moonlite and BEPI-Columbo are not to going be weighed in the same balance. At the very least, future involvement in a next-generation X-ray telescope should certainly have been in the mixer with other observatory-type facilities on the ground. I fear that the STFC Executive sees the current UK ground-based programme as significantly too large, and would like to squeeze it all into the box marked ESO. I would like to be able to sound more optimisitic, but I think that the most likely outcome of this review is therefore that the only current facilities that will survive into the medium term will be those provided through ESO membership. JCMT and UKIRT are nearing the end of their useful life anyway, but the writing is definitely on the wall for both Gemini and E-Merlin. Not that it hasn’t been before now…

If this the way things go, then the remaining issue is whether we can afford to be involved in both E-ELT and SKA, which seems to me to be most unlikely. If we have to pick one, which should it be? That is clearly going to be the topic of much debate. In the spirit of the drive for rationalisation I touched on above, it may well be that we don’t do anything at all outside the ESO umbrella. In that case the United Kingdom ends up with a ground-based astronomy programme consisting of the ESO facilities plus a share in the E-ELT (itself an ESO proposal). I think this would be a tragedy because I find the scientific case for SKA much stronger than that for E-ELT; it would have been a closer call if the ELT were still the 100m optical telescope as originally proposed many years ago (and which I used to call the FLT). I’m sure many will disagree for legitimate scientific reasons (rather than the desire to play “mine’s bigger than yours” with the Americans, who are currently developing a 30m telescope).

I’m sure there will also be many astronomers who would rather have neither SKA nor E-ELT if it means losing access to the suite of smaller telescopes that continue to produce many interesting scientific results. If it came to a vote I’m not sure what the result would be, which is why I want to encourage anyone who has any input to fill in the questionnaire!

A final little wrinkle on this question is the following. Suppose STFC decides not to support future involvement in SKA – I hope this isn’t the way things turn out, but in our dire financial circumstances it might be – does this make continued funding for E-Merlin more likely or less likely? Answers on a postcard (or even via the comments box)..

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